Mobility of 〈100〉 and 〈110〉 Dislocations in B.C.C. Iron

It is proposed that dislocations with 〈100〉 or 〈110〉 Burgers vectors should move on {110} planes in body-centred cubic metals about as easily as does a ½〈111〉 dislocation; the suggestion may help to explain the recent discovery of many such dislocations in iron. Thus, in the (110) plane, the large atomic hill facing a displacement of 〈001〉 can be avoided if the displacement follows a curved path approximating first to ½[111] and then to ½[111], in which case the friction stress will be similar to that for the ½〈111〉 displacements.